Install CyanogenMod 10.2 Jelly Bean 4.3 custom ROM on Galaxy S3 I9300

Samsung and their Galaxy S3 I9300 have an unofficial Jelly Bean 4.3 CM10.2 custom ROM to bring a whole new dimension to its performance. Not that the smartphone does not perform well. It just needs a tool to make it deliver more greatness.

The new ROM has the help of various features and other additions; like Bluetooth pairing with devices that deliver low power, virtual surround sound and so on.


Requirements are now upon us:

All is settled for the coming of the steps below. Follow them and your smartphone will be updated to unofficial CM10.2 custom ROM.Galaxy-S3-GT-i9300


  1. Plug, for the time being, your I9300 to your notebook; then take the Gapps and the unofficial CyanogenMod 10.2 archive from your notebook to your handset’s SD card root.
  2. Disconnect the devices. Switch the handset off after that. Simultaneously press and hold Power, Volume Up and Home to enter the device into Recovery Mode; when the manufacturer’s logo is on the phone’s display, let go of the keys for a bit, then hold them and you will be shown the Recovery Mode.
  3. To perform the next step, you need to first operate some wiping actions:
    – choose, for the first one, the option called Factory reset/Wipe data;
    – confirm it via the selection of “YES”;
    – return to the Recovery Menu after the wiping has finished;
    – opt for Wipe Cache Partition;
    – choose Wipe Dalvik Cache.
  4. Below you will see what sort of options to select next:
    – “Install zip from SD card”;
    – “Choose zip from SD card”.
  5. The cm-10.2-20130727-UNOFFICIAL-i9300 .zip must now be opted for with POWER and then you have to confirm the flashing like this:
    – wait for a screen to show up
    – choose Yes – Install …zip.
    This will make the installation of the firmware start at once.
  6. The Google Apps archive file will then have to be installed, too. For that, you should repeat the actions performed when you flashed the other file.
  7. Return to the Recovery Menu after that. Choose, from that place, the system restarting option. The Galaxy S3 GT-I9300 will boot into the update firmware.
  8. Now that the guide has just been completed, you should go all the way and discover what the new ROM does well to your smartphone.

NOTE: In case you upgrade from CM10/10.1, you have to do as follows:

  • copy the Gapps and the new ROM zip files to the handset’s SD card;
  • boot your phone into Recovery Mode;
  • install, afterwards, the new ROM from the device’s SD card;
  • install the Gapps from the same location;
  • wipe the system;
  • reboot the phone.

Should you upgrade the handset from a past CM10.2 version, you need to:

  • transfer the ROM archive to the device’s SD card;
  • then enter the phone into the Recovery Mode;
  • flash the tool from the SD card;
  • reboot the handset.

You can return to the ROM that used to be sported by your phone if you do as indicated below:
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  • boot the Galaxy S3 I9300 into Recovery;
  • opt for Backup&Restore;
  • choose your ROM from a list;
  • wait for it to be back on your phone.

The possible problems you will experience after the update is done include the possibility of the storage to crash, issues with the graphics and SMS subject to crashing.

Should the problem of a boot loop occur, you can:

  • go to Wipe Cache Partition and select it;
  • have patience till this wiping action is over;
  • go to Wipe Dalvik Cache and opt for it;
  • wait for this second wiping task to end;
  • reboot the phone.